Fabulous, thanks very much PHV.
Ugly looking statement now but it works;
awk -F, '{lhs=$6*($10<1000000?1000000:$10);rhs=($7<1000000?1000000:$7)*$9;tot=($7<1000000?1000000:$7)+($10<1000000?1000000:$10);sum=(lhs+rhs)/tot};{print $2,$6,$7,$9,$10,$(NF-3),$(NF-2),$(NF-1),$NF,sum}'
Much...